function changeCSS(sURL){
var obj = document.getElementsByTagName("link");
for (var i=0, cnt=0; i<obj.length; i++)
{
if (obj[i].type == "text/css") obj[i].href = sURL[cnt++];
}
}

myW = window.screen.width;
if((myW) < 1100){changeCSS(["base-custom.css"]);}